How ISIS Prepares For War: In Mosul, Islamic State Has A Moat, Bombs, Exploding Oil Trucks And Other Tricks To Stop Iraqi Military

The Islamic State group is protecting its largest territory by building a moat around the northern Iraqi city of Mosul. The construction plan comes as President Barack Obama and foreign leaders have vowed to take back the largest city in the militant group's so-called caliphate.

ISIS also plans to build tunnels across the city to block government troops, set out explosives and shut down certain neighborhoods to further bolster its security. Oil tanks are being positioned along the city's border to create a circle of fire should troops reach Mosul, Reuters reported Wednesday.

"I can see Daesh digging tunnels everywhere and covering the entrances with sewage covers. My neighbour's house is now part of a network of tunnels that reaches across the city," a resident from the Sumer district of southeastern Mosul told Reuters.

Mosul, home to 2 million people and Iraq's second largest city, fell to ISIS in 2014. It quickly became the epicenter of the militant network, with its leader Abu Bakr al-Baghdadi declaring a modern caliphate spanning large parts of Iraq and Syria from the city's main mosque. Iraqi-based Alsumaria TV recently claimed that al-Baghdadi had been spotted in Mosul amid the military struggle.

Iraqi and U.S. officials are expected to launch a battle to reclaim the territory in October. Military leaders in Syra and Iraq have already seized back control of various former ISIS territories, weakening the militant group's vision for a caliphate that would stretch across the Middle East.

"Oil trenches, tunnels and suicide attacks will not save Daesh from defeat but they will make the battle more challenging," Sabah al-Numani, a spokesman for the counter-terrorism forces leading the offensive, told Reuters. "We are confident Daesh will fight to their last fighter to keep holding Mosul."

Iraqi Prime Minister Haider al-Abadi has vowed to free Mosul by the end of the year. The war is expected to take a significant toll on civilians with a flurry of fires, airstrikes and homemade bombs.